Corrosion- and fungus-inhibiting composition



y 1960 A. WACHTER EI'AL 2,943,909

CORROSION- AND FUNGUS-INHIBITING COMPOSITION Filed Aug. 26. 195? SODIUM NITROPHENATE AMINE, PHENATE AMINE PHENATE AMINE NITRITE SODIUM PHENATE AMINE NITRITE A l l B c U- o (I) FIG. I

L; 2 LL] I 0.

l l l l I I I J 2 4 s 8 IO [2 2o 22 DAYS c AMINE PHENATE AMINE NITRITE o SODIUM PHENIATE+AMINE NITRITE E AMINE NITRITE c (D FlG.2

AMINE NITRITE 2 6 IO I4 22 DAYS INVENTORSI AARON WAC HTER RITA WIELAND CORROSION- AND FUNGUS-INHIBIIING COMPOSITION Aaron Wachter, Oakland, and Rita Wieland, Berkeley, Calif., assiguors to Shell Oil Company, a corporation of Delaware Filed Aug. 26, 1957, Ser. No. 680,162

6 Claims. (Cl. 21-2.7)

This invention is concerned with compositions useful for the reduction in fungus growth and corrosion. More particularly, it is directed to compositions useful for the prevention of corrosion of metallic surfaces and simultaneous inhibition of fungus growth during storage of metals.

One of the most pressing problems in the storage of metallic items is corrosion of their surfaces due to the presence of oxygen and water vapor. Corrosion can be inhibited by smearing the metallic parts with an oil or grease-like material or by coating them with a strip plastic composition. However, each of these involve manual operations adding to the cost of preparation of storage and elimination of the protective coating before the article can be used. A much more convenient and less costly means of inhibiting corrosion comprises confinement of the metallic parts in an enclosed space such as by paper or other wrapper and including in the enclosed :space a corrosion inhibitor chosen to volatilize slowly but effectively during the storage period, thus providing a constant means of protecting the surface against corrosion without necessitating the manual preparation or cleauingof the article for this purpose. Such inhibitors are normally referred to as vapor phase inhibitors. The most effective class of such items comprises the amine nitn'tes and certain mixtures of these preferably containing a basic acting agent so as to maintain a pH at least above about 6.0.

Under certain conditions such as high humidity and/ or high temperature, one complicating factor appears in the use of vapor phase inhibitors, namely, the growth of fungus within the enclosed space and consequent interference with the process of vapor phas'e'corrosion inhibition; While it is true that fungus growth normally occurs on organic surfaces such as cloth'or plant fibers or the like, under many tropical conditions it has been found that fungi grow on other surfaces as well, such as glass, metal, wood, etc. Under these conditionsand particularly when the fungus grows or touches the metal surface it has been foundth'at vapor phase corrosion inhibition of'that area so effected is not satisfactory and rusting or corrosionoccurs. I

It is an object of the present invention to provide a means for controlling both corrosion and fungus growth. It is another object fthis invention to provide an improved vapor phase inhibiting composition which is also fuiigic'idal. It is a further object of this invention to provide a means of preventing corrosion and simultane United States Patent 0 2,943,909 Patented July 5, 1960 ice 350, both salts having vapor pressures of at least about 0.00002 to mm. Hg at 21 C. Still in accordance with the present invention wrapping materials are provided comprising a solid inactive packaging material, such as paper, having the above compositions physically associated therewith. Also according to the invention a method is provided for inhibiting fungicidal growth (on organic or inorganic surfaces) and corrosion by maintaining a metal in the immediate presence of an atmosphere containing the two salts as stated above.

Free phenols cannot be mixed with nitrite salt since, due to the acidic nature of the phenol, the nitrite salts are rapidly decomposed. It is possible to combine a metallic salt of a phenol with a nitrite salt but for some reason this has been found to drastically reduce the rate of vaporization of the nitrite salt. Since it is highly desirable to maintain the original rate of vaporization of the nitrite salt so that efiicient and complete corrosion inhibition is maintained, it therefore is undesirable to combine metallic salts such as sodium phenates with the nitrite salt.

It has been found, however, that the amine salts of phenols do not adversely affect the rate of vaporization of the nitrite salt. Conversely, the presence of nitrite salts has been found to cause rapid depletion of theconcentration of sodium salts of phenols from their compositions, either by increasing the rate of vaporization or by actual decomposition of the metallic salt of the phenol. On the other hand, however, the combination of nitrite salts with amine salts of phenols causes substantially no change in the rate of vaporization of the amine phenate than that experienced when the latter is utilizedin the absence of the nitrite salt. Consequently, it will be seen that the present invention takes advantage of these two sets of phenomena in utilizing the combination of the amine phenate and the amine nitrite for the combined purpose of corrosion inhibition and fungicidal properties without adversely affecting the rates of vaporization of either the nitrite or the phenate. Furthermore, it has been found that a moderate synergistic effect is experienced with respect to corrosion inhibition by the combination of the two materials. A v v The nitrite salts can be utilized as inorganic salts either metallic or ammonium but preferably are organic base salts and more particularly, the organic nitrogen base nitrites. The nitrites and the phenates can be prepared from the same classes of organic bases, particularly organic nitrigen bases, or may be utilized in the form of different organic base salts.

Representative classes of organic bases which are suitable for preparing the salts used as vapor phase inhibitors according to the present invention include: primary amines, secondary amines, tertiary amines, cyclic secondary amines of the type of piperidine, oxazines, morphciline, thiazolines, and pyrrolidines; and various nitrogenous bases such as urea, thiourea, hydrazines, hydroxylamines, amidines, and guanidine. In any of the above nuclei, alkyl cycloalkyl, terpinyl, bornyl, aralkyl, beri'zfyl, phenyl, aryl and various substituent groups or' atomic radicals may be present so long as the sum total basicity of the nitrogenous compound is approximately equalto or greater than the acidity of nitrous acid with which it forms a salt. Among the substituent groups the alkyl and cycloalkyl groups are preferred.

The basicity of the various basic constituents of the class of salts disclosed herein is described, for example, in The Organic Chemistry of Nitrogen, by N. V. Sidgwick, 1937 edition, and in Organic Chemistry, by Paul Karrer, 1938 edition.

More specifically and preferably, organic nitrogen base salts of nitrous acid include the following nitrite salts of:

(1) Primary amines, such as (a) primary amines in attached to a secondary or a arealiphatic, alicyclic,-heterocyclic, aromatic, or alkylatedkyclic radicals, and may, if desired, contain preferably not more than one olefinic double bond, or R and ,and Rg are joined in the form of a cyclo-aliphatic or heterocyclic-aliphatic ring radical R (b) primary amines in which the amine group is attached to an aralkyl group as in the following structural formula:

. whe'rein R is an aromatic hydrocarbon radical, preferably a phenyl or alkylated phenyl radical and'n is an ,integer which is preferably 1 or 2; primary aliphatic amines, such as methyl amine, which react with nitrous acid in the presence of an excess of the amine to give a.

primary amine nitrite salt (as distinguished from a primary aliphatic amine which reacts with nitrous acid to fyield. nitrogen, an alcohol, or other reaction products).

(2) Secondary amines, such as: those in which the i amine group is attached to an aliphatic carbon atom, preferably a secondary or tertiary carbon atom, as represented by the following structural formulas:

wherein R and R are hydrocarbon radicals as in l (a) 1 'and wherein R and R may be joined in the form of a ring forming A RsNH V which is either N-alicyclic or contains in the R portion of the organic ring atoms of the type of oxygen and/or 'fsulfur.

p (3 Tertiary amines. (4) Quaternary ammonium bases including pyridinium bases.

Specific examples of organic nitrogen bases suitablefor preparation of the amine-nitrite salt vapor phase'corrosion inhibitors of the present invention include:

Primary amines: methylamine, isopropyl amine,

' Z-amino-butane, tertiary butyl amine, 2-amino-4-methylpentane, various amyl, hexyl, heptyl, octyl, and higher homologous primary amines wherein the amine group is attached to a secondary or tertiary carbon atom; cyclopentyl amine, alkylated cyclopentyl amines, cyclohexylamine, .monomethylcyclohexylamines, dimethyl cyclohexylamines, trimethyl cyclohexylamines, other alkylated 'cyclohexylamines, bornyl amine, fenchyl amine, cycloterpenyl amines, pinyl amine, benzylamine, betaphenylethylamine, alkylated benzylamines, tetrahydro betanaphthylamine, allyl amine, beta-methyl allyl amine, beta- N-alkyl N-bornyl amine, di-bomyl amine, N-methyl N-cycloterpenyl amine, N-isopropyl N-( 1 )menthyl amine,

N-alkyl N-benzyl amines and their homologs and analogs;

dicyclopentyl amine, dicyclohexyl amine, alkylated dicyclohexyl amines; diphenylamine, dibenzylamine, di-

(beta phenyl ethyl) amine; piperidine, piperazine, alkylated piperidines or piperazines; 1,4-alkylated and unalkylated oxazines such as morpholine and zlli fi't methyl tetrahydro-l,3-oxazine; alkylated-1,3-thiazolines.

fwherein'R R and R are hydrocarbon radicals which such as 2,4,4,6tetramethyl tetrahydro-3-thiazoline.

Secondary amine type derivatives of alkylene diamines,

such as:

wherein R and R maybe like or different aliphatic, alicyclic aralkyl, alkarylalkyl, heterocyclic, terpenic radicals, and wherein R is an alkyleneradical. These R and R radicals for instance, may be isopropyl, butyl, cyclohexyl, benzyl, and/ or bornyl radicals. The R2 radical is preferably an ethylene or propylene radical.

Tertiary amines: trimethyl amine, triethylamine, tri-npropylamine, tri-isopropylamine, tributylamine, higher homologous and isomeric trialkylamines, variously N-substituted tertiary amines having'diiferent organic radicals on the amino nitrogen atom, e.g., alkyl, alicyclic, bornyl, fenchyl, aralkyl, and like homologs and analogs; and tertiary amine type derivativesof alkylenediamines;

Quaternary ammonium bases: tetramethyl and higher -tetraalkyl ammonium bases; trimethyl benzyl-, trimethyl cyclohexyl-, tributyl decyl ammonium bases; various quaternary N-substituted ammonium bases-having various organic radicals (of the'type described above) on the quaternary nitrogen atom; pyridinium and alkylated pyridinium or quinolinium quaternary ammonium bases having an alkyl, cycloalkyl, or aralkyl group on the I quaternary nitrogen atom, including methyl, butyl, cyclohexyl, benzyl' groups and like homologs or analogs. V

The various hydrocarbon radicals or groups of .the above amines may also contain stable and inert'polar substituent atoms or radicals, such as, chlorine, ether, thio-ether, alcohol, free amino, or nitro groups. Neutral ketone, ester and nitrile groups, and'aliphatic unsaturation may also be present, particularly in the case of allyl and chlorallyl groups.

The phenols which may be combined with the above types of amines to form the amine phenates suitable for use in the present invention include any phenols and substituted phenols having molecular weight less than about 350. These include especially the nitro and chloro phenols although polyhydrdxy phenols and alkylphenols Dicyclohexylamine salt of 2,4-dinitrophenol Diisopropylamine salt of dinitrophenol Dicyclohexylamine salt of dinitro-o-cyclohexylphenol Diisopropylamine salt of dinitro-o-cyclohexylphenol Dicyclohexylamine salt of o-nitrophenol Diisopropylamine salt of o-nitrophenol Dicyclohexylamine salt of dinitro-o-cresol Dimethylamine salt of 4,6-dinitro-2-sec.-butylphenol Di-sec.-butylamine salt of 2,4-dinitro-alpha-naphthol Isopropylcyclohexylamine salt of 4-n-propyl-2-aminophenol Di(2-ethylhexy1)amine saltof a mixture of isomeric diaminophenols Diethanolamine salt of 2,4,5-trichlorophenol Dicyclohexylamine salt of o-chlorophenol Dicyclo'pentylamine salt of meta-chlorophenol Di(2-ethylbutyl)amine salt of mixed monobromophenols Dicyclohexylamine salt of 2,4-dichlorophenol Diisopropylamine salt of 2,4,5-trichlorophenol Ethanolamine salt of 2,4,6-trichlordphenol piisobutylamine salt of para-chloro-ortho-cresol Dihexylamine salt of mixed cresols As stated hereinbefore, it is possible to utilize inorganic nitrites as well as amine nitrites in the present compositions. These include the alkali metal nitrites such as sodium, lithium, or potassium nitrites as well as the alkaline earth metal nitrites including calcium and magnesium nitrites. Ammonium nitrite may be used in addition to or in place of other nitrite salts.

It is preferred practice when utilizing an inorganic nitrite to include together therewith 0.05-20 parts by weight of a diamide for each part of the'inorganic nitrite.

Amide's, which have been successfully used, fall into the groups of mono-amides, diamides, and polyamides. By the term mono-amide is meant a compound having the general formula R-(J-NH:

where R is an aliphatic group having from 1 to 18 or 25 or more carbon atoms. These include such amides as acetamide, propionamide, and N-bu'tyramide, N-v'aleramide, stearamide, palmitylamide, fatty acid amides, and the like. Although less activity results when R is aromatic or aliphatic-aromatic, amides of that type may be used. For example the amide component may be benzamide and the aromatic acid amides of the'type benzene sulphonic acid amide, toluene sulph'o'nicacid' amide, naph thalene sulphonic acid amide, and the like.

Best use is made of the diamides having the formula where R is hydrogen or an organic radical of the type previously described. Illustrative of suitable diamides are urea, N-substituted ureas, and unsymmetrical ureas, such as N-N-dibutyl urea, N-butyl urea, N-propyl urea, dimethyl urea, t-butyl urea, ti-amyl urea, and the like, and other diamides, such as buramines (the reaction product of amines such as butyl amine with urea), the reaction product of amines with biuret, and guanidine and derivatives thereof. A suitable polyarnide is illustrated by biuret.

It is especially advantageous to ensure that the composition utilized has a pH above about 6.0. This can be effected by addition of such basic acting agents as are referred to in US. Patent 2,752,221.

The amine salts of the phenols may be prepared by simply dispersing the phenol and the amine in solvents, mixing them and thereafter evaporating the solvent. The same is true of the preparation of amine nitrites although it is preferred to form a solution of an amine phosphate and add thereto a solution of sodium nitrite or potassium nitrite in order to form the resultant amine nitrite. Methods of the latter type are disclosed in US. Patent 2,717,843. It is, of course, possible to utilize a combined process so that the mixture of nitrite and phenate may be formed in a single process rather than separately. Such a process comprises formation of a solution of an amine phosphate, preferably in alcohol or aqueous alco' hol, followed by addition thereto of a solution (alcoholic) of the phenol in an amount suflicient to form an amine phenate with only a portion of the amine phosphate, the third step being the addition of suificient nitrite such as sodium nitrite to react with the remaining portion of amine phosphate, thus creating a mixture of amine nitrite and amine phenate.

The vapor phase corrosion inhibitor and fungicide both atlases should preferably have vapor pressures in excess of about 0.00002 mm. Hg at 21 C. and better results are 'obtained with a composition in which both of the nitrite and the phenate have vapor pressure greater than about 0.0001 mm. Hg at 21 C. The compositions are ruseful for preventing the corrosion and inhibiting fungus growth upon various ferrous metals such as steels and as well as combinatio'ns of steel with zinc or copper or other metals and aluminum as well as alloys of these metals. Of course, the compositions also will inhibit-or prevent fungus growth on other organic orv inorganic-surfaces (such as cloth, paper or other packaging materials) with which they come in contact. I

In one of the preferred embodiments of the present invention it is found advantageous to utilize a solid wrapping material such as paper which has been impregnated with the compositions disclosed herewith. The metal articles are then wrapped in the paper to obtain the dual inhibiting functions of the composition. .OnIthe other hand, of course, it is possible to simply dispos'ethe composition in powdered form or otherwise in metal articles such as cylinders or the like in orderto prevent corrosion and inhibit fungus growth. While it is preferred under most circumstances to utilize compositions containing from 25 to of either thenitrite or the'phenate, it is also possible to utilize from 10-90% of the nitrite and 90-10% of the phenate dependent upon the severity of corrosion or of fungus growth as Well as the humidity and temperature conditions involved in a specifie use.

The following compositions illustrate the type of compositions useful for use in the present invention:

Composition A:

50% dicyclohexylamine nitrite 50% dicyclohexylamine o nitrophenate Composition B:

25% diisopropylamine nitrite 75 diisopropylamine salt of 2,4-dinitrophenol Composition C:

75 diisobutylamine nitrite 25% dicyclohexylamine salt of mixed cresols Composition D:

30% sodium nitrite 30% urea 40% dicyclohexylamine salt of 2,4-dinitro-6-cyclohexylphenol Composition E:

40% ammonium nitrite 30%N-butyl urea 30% ethanolamine salt of 2,4,6-trichlorophenol Composition F:

% diisopropylamine nitrite 15% diisopropylamine salt of 2,4,5-trichlorophenol Composition G:

15% di-(Z-ethylhexyl) amine nitrite 85 di(2-ethylhexyl)amine salt of 2,4-dinitro-ocresol Example I When steel plates are wrapped in paper and stored under high humidity conditions at temperatures of about -110 F., rapid corrosion of the surface of the plate occurs. When storage is conducted while mold spores are present, it is found at the end of a one-month storage period that mold growth occurs on both the interior of the paper wrapper and on portions of the steel surface. When small amounts of dicyclohexylamine nitrite are present, the corrosion is reduced by a factor of 5 and when one-half of the nitrite is replaced with an equal amount of dicyclohexylamine ortho nitrophenate, the corrosion rate was reduced by a factor of 75. At the same time, although mold spores are present and mold growth. occurs when the phenate is not utilized, no mold growth. is noted when the phenate is used for partial replacement of the nitrite.

pound kraftpaper v(A) was modified by depositing therei.

on 1.0 gram-per square ft. of sodium ortho nitrophenate, on a second sample (B) the dicyClohexylaminexsalt of 'ortho nitro phenate, a third sample (C) containing a 50-50 mixture. of, the amine phenate and dicyclohexylaminenitrite and a fourth sample (D). containing sodium ortlionitro';phenate with an'equal amount of dicycloshexylamine nitritel :Thesesa'mples were exposed at room temperature (6080 F.) in an active air stream and .the amount; of phenateremaining .onxithe paper was periodically tested. Fig. I shows that 'the sodium or iamine salts .of :the phenol when present alone on the paper had substantially the same rate of volatility orat leastthes'ame rate of retention on the paper. However, :when these phenates' were modified with an equal amount phenate increased sharply while the rate of'depletion -of. the amine phenate remained substantially unchanged.

.Eqcamplelll Samples C and D were analyzedperiodically after exposure to the same conditions for amine nitrite retention. Also a sample B, containing 1 g./sq.' ft. of the amine nitrite was tested under the same conditions. Fig. 11 shows that'the addition of amine phenate to the amine .nitrite' did not substantially alter the rate of vaporization of the amine nitrite. However, the addition of sodium phenate resulted in a substantial reduction in the volatility ofthe nitrite.

We claim as our inventionz' 1. A composition comprising about 25+75% by weight of dicyclohexylammonium nitrite and about 751-25 by weight of dicyclohexylammonium. nitrophenate.

of:=the*amine=n'itrite the rate of depletion ,of the sodium 2 '8 2. A composition comprising about 25-75% by weight of a nitrite'of thefgroup 'consisting of'dicyclohexylarm,

monium nitrite, and diisopropylammonium nitritQIand about 75-25% .byweight of anin'ophenate of the group consisting of cycloh'exylammoniuni. introphenate and di-.

cyclohexylammoiiium nitrophe'nat'e.

3. A substantiallysolid inactive packaging material having physically associated therewith a composition according to claim 1.

4. A substantially solid inactive packaging material having physically associated therewith a composition according to claim 2. r

- 5. In a method for inhibiting both fungus growth on andcorrosion'of a'metal normally corrodible bycontact with water vapor and oxygen, the step comprising maintaining in the immediate presence of said metal an atmosphere containing va corrosion inhibiting and. fun- :g'icidal concentration of a composition according to claim 1.

6. In a method for inhibiting both fungus growth'on and corrosion of a metal normally corrodible by con tact withvapor and oxygen, the step comprising maintaining in the immediate presence of said metal an atmosphere containing a corrosion inhibiting and fungicidal concentration of a composition according to claim 2.

7 References Citedin'th file of this patent UNITED STATES PATENTS 

2. A COMPISITION COMPRISING ABOUT 25-75% BY WEIGHT OF A NITRITE OF THE GROUP CONSISTING OF DICYCLOHEXYLAMMONIUM NITRATE AND DIISOPROPYLAMMONIUM NITRATE AND ABOUT 75-25% BY WEIGHT OF A NITROPHENATE OF THE GROUP CONSISTING OF CYCLOHEXYLAMMONIUM NITROPHENATE AND DICYCLOHEXYLAMMONIUM NITROPHENATE. 